In robotic manipulators and other similar devices, various bearings for movable parts must be anchored to such robots to provide pivot points about which those moving parts can rotate. When standard tapered bearings are used, a bearing retention shoulder must be formed within such bearing anchor to properly retain the bearing therewithin. For example as described in U.S. Pat. No. 4,392,776, which was issued L.Y. Shum on July 12, 1983, a pair of oppositely disposed shoulders can be used to exert a diagonal clamping action on angular contact bearings to obviate backlash which can arise in conventional bearings However, as shown in FIG. 3 of the Shum patent, the resulting diagonal clamping action does not provide uniform clamping around the periphery of such bearing. Moreover, moving parts often have various pivot points which must be accurately aligned relative to one another for proper movement of such parts and for protection of their often delicate structures. Such alignment of moving parts, bearings and bearing retention shoulders often involve relatively complex alignment procedures with relatively small margins for error. Where permanently located bearing shoulders are involved, this alignment can be costly, time consuming and necessarily repeated often. For example, alignment done during a manufacturing phase of a machine may be adversely affected by the hazards of shipment and/or installation.
On the other hand, some types of bearings are axially self-contained. For the purposes of this disclosure, the term "self-contained" shall connote bearings which do not require additional containment structures such as the shoulder for tapered bearings. A bearing block for such bearings is commonly made by drilling a bore through such bearing block the same size as the outer diameter of the self-contained bearing, then splitting the bearing block through such bore to facilitate insertion of the bearing therewithin and later clamping of the cut half of the bearing block over the contained bearing. By cutting the bearing block through the bore formed therewithin, there is formed a gap between the two resulting pieces. When a bearing having an outside diameter equal to the bore diameter is placed therewithin, the bearing block pieces impose compressive forces on such contained bearings when clamped together.
However, in this traditional manner of clamping a self-contained bearing, because the bore formed within the bearing block is the same size as the outer diameter of the bearing, and due to the fact that there is now a gap between these two pieces of the bearing block, the inward compressive forces established by such bearing block parts upon the contained bearing tend to be concentrated in the closed ends of the bearing bore around only the top and bottom portions of the bearing. Because the bearing bore is the same size as the outer diameter of the bearing near the interface of the two parts of the bearing block, relatively no inward compressive forces are exerted on the bearing in these areas. Consequently, the uneven compressive forces tend to deform the bearing slightly, causing it to become out-of-round or egg-shaped, unless shims are carefully placed at the correct points between the bearing blocks and the bearing. Such shimming procedures are time consuming, costly, and not totally reliable Improper shimming can lead to premature deterioration and failure of such bearing. Such shimming procedures can also adversely affect alignment of the moving part of the robotic manipulator.
As can be seen from a look at these standard industry structures, procedures and techniques, there remain definite problems in effectively anchoring bearings for moving parts of robotic manipulators in such a way as to ensure proper bearing installation while allowing relatively convenient aligning of such moving parts and replacement of worn bearings from time to time. With prior bearing block structures and methods, costly and time consuming alignment procedures were necessary, as well as difficult and often intricate shimming operations. The bearing block assembly which could provide relatively rapid installation, obviate a need for shims, and at the same time simplify alignment procedures was not available in the industry heretofore.